Dynamic operating system optimization in parallel computing

ABSTRACT

A method for dynamic optimization of thread assignments for application workloads in an simultaneous multi-threading (SMT) computing environment includes monitoring and periodically recording an operational status of different processor cores each supporting a number of threads of the thread pool of the SMT computing environment and also operational characteristics of different workloads of a computing application executing in the SMT computing environment. The method further can include identifying by way of the recorded operational characteristics a particular one of the workloads demonstrating a threshold level of activity. Finally, the method can include matching a recorded operational characteristic of the particular one of the workloads to a recorded status of a processor core best able amongst the different processor cores to host execution in one or more threads of the particular one of the workloads and directing the matched processor core to host execution of the particular one of the workloads.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to parallel computing in general and moreparticularly to operating system optimization in a parallel computingenvironment.

2. Description of the Related Art

Parallel computing is a form of computation in which many calculationsare carried out simultaneously, operating on the principle that largeproblems can often be divided into smaller ones, which are then solvedconcurrently. There are several different forms of parallel computing,for example bit-level, instruction level, data, and task parallelism.Parallelism has been employed for many years, mainly in high-performancecomputing. More recently, parallel computing has become the dominantparadigm in computer architecture, mainly in the form of multicoreprocessors.

Parallel computers can be classified according to the level at which thecomputing hardware platform supports parallelism—with multi-core andmulti-processor computers having multiple processing elements within asingle machine, while clusters and grids using multiple computers towork on the same task. Specialized parallel computer architectures aresometimes used alongside traditional processors, for acceleratingspecific tasks. The advent of simultaneous multi-threading (SMT)operating environments specifically supports parallelism by executingmore than one thread on a processor core and assigning different tasksof a computer program to different threads.

Thus, managing the assignment and execution of different processingtasks to different threads of execution can in of itself requiresophisticated programmatic logic. While more programs can runsimultaneously in an SMT environment, the performance of some ofprograms may show some degradation. Consequently, administrators becomeunsure about the effectiveness of SMT for workloads of interest andultimately disable intelligent usage of SMT. Ironically, based upon theexhibited degradation of the workloads of interest, the administratorsubsequent to SMT deactivation can experience a decrease in throughputof the workload of interest while the performance of the individualapplications of the workload of interest are ensured.

Even still, in large enterprise level systems, the numerous tasksrunning on huge systems face performance issues that often cannot berecreated for troubleshooting, but can most-often be traced tonon-optimal utilization of the system. In this regard, not only are theworkloads varying constantly, but also the characteristics of a singleapplication can vary from time to time. Of note, program characteristicsdetermine whether leveraging of SMT will help increase to throughput orif the use of SMT will degrade performance of a subject workload. Giventhe dynamic nature of the workloads that run on the system, the SMTcontrol has to be dynamic as well. Notwithstanding, currentmethodologies permit either a system-wide activation or de-activation ofSMT and do not allow for a partial activation, or even dynamic SMTcontrol. Consequently, critical resources of the computing environmentare likely to be wasted.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention address deficiencies of the art inrespect to workload optimization in an SMT environment and provide anovel and non-obvious method, system and computer program product fordynamic optimization of thread assignments for application workloads inan SMT computing environment. In an embodiment of the invention, amethod for dynamic optimization of thread assignments for applicationworkloads in an SMT computing environment can include monitoring andperiodically recording an operational status of different processorcores supporting one or more threads comprising a thread pool of the SMTcomputing environment and also operational characteristics of differentworkloads of a computing application executing in the SMT computingenvironment. In this regard, the operational characteristics can includea number of clock ticks consumed by a corresponding one of theworkloads, a higher number of clock ticks indicating a higher degree ofactivity. Additionally, the operational characteristics can include ameasurement of cycles per instruction (CPI) consumed by a correspondingone of the workloads and a variance in measurements of CPI consumed bythe corresponding one of the workloads over time, a lower varianceindicating greater stability in operational characteristics or behavior.

The method further can include identifying by way of the recordedoperational characteristics of the different workloads a particular oneof the workloads demonstrating a threshold level of activity.Optionally, a particular one of the workloads can be identified by wayof the recorded operational characteristics of the different workloadsas demonstrating both operational stability and a threshold level ofactivity. Finally, the method can include matching a recordedoperational characteristic of the particular one of the workloads to arecorded status of a processor core best able amongst the differentprocessor cores to host execution of the particular one of the workloadsin one or more of the threads in the thread pool and directing thematched processor core to host execution of the particular one of theworkloads. In one aspect of the embodiment, it can be determined that noone of the processor cores is available to host the execution of theparticular one of the workloads, and in response, an existing assignmentof ones of the different workloads to corresponding ones of theprocessor cores and/or the number of threads hosted (enabled) on one ormore of the cores can be re-arranged to optimize matching of therecorded operational characteristics of the ones of the differentworkloads to the recorded operational status of the processor cores.

Additional aspects of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The aspectsof the invention will be realized and attained by means of the elementsand combinations particularly pointed out in the appended claims. It isto be understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof this specification, illustrate embodiments of the invention andtogether with the description, serve to explain the principles of theinvention. The embodiments illustrated herein are presently preferred,it being understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown, wherein:

FIG. 1 is a pictorial illustration of a process for dynamic optimizationof thread assignments for application workloads in an SMT computingenvironment;

FIG. 2 is a schematic illustration of a parallel computing dataprocessing system configured for dynamic optimization of threadassignments for application workloads in an SMT computing environment;and,

FIG. 3 is a flow chart illustrating a process for dynamic optimizationof thread assignments for application workloads in an SMT computingenvironment.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention provide for dynamic optimization of threadassignments for application workloads in an SMT computing environment.In accordance with an embodiment of the invention, operationalcharacteristics of application workloads executing within an SMTcomputing environment can be monitored and recorded. Concurrently, theoperational status of different processor cores of a processor pool forthe SMT computing environment can be monitored and recorded. Responsiveto detecting a particular application workload achieving an thresholdactivity level indicative both of operational stability and a highdegree of activity (“hotness”), the recorded operational characteristicsof the particular application workload can be mapped to the operationalstatus of the SMT computing environment to identify an available one ofthe processor cores optimally matched for the particular applicationworkload. Thereafter, the particular application workload can beassigned to the identified available processor core. Of note, to theextent that an available processor core cannot be mapped to theparticular application workload, existing workload assignments for thedifferent processor cores in the processor pool can be re-organized toaccommodate an optimally largest number of workloads demonstrating anactivity level beyond the pre-determined threshold.

In further illustration, FIG. 1 is a pictorial illustration of a processfor dynamic optimization of thread assignments for application workloadsin an SMT computing environment. As shown in FIG. 1, the status 120 of aset of processor cores 130 hosting different processing threads 170 canbe monitored and recorded. Likewise, the operational characteristics 110of different workloads 150 in an SMT environment 160 can be monitoredand recorded. SMT optimization logic 140 can inspect the operationalcharacteristics 110 of the workloads 150 to identify ones of theworkloads 150 demonstrating both operational stability and also arequisite degree of high activity (“hotness”).

Upon identifying a particular one of the workloads 150 demonstratingoperational stability and the requisite degree of hotness, the SMToptimization logic 140 can compare the operational characteristics 110of the particular one of the workloads 150 to the status 120 of theprocessor cores 130 to identify a particular one of the processor cores130 able to support one or more threads 170 to host the operation of theparticular one of the workloads 150. To the extent none of the processorcores 130 are available and suitable to support one or more threads 170to host the operation of the particular one of the workloads 150, theassignment of existing ones of the workloads 150 to correspondingthreads 170 in the processor cores 130 can be re-arranged by the SMToptimization logic 140 according to the current status 120 of theprocessor cores 130 and the operational characteristics 110 of theworkloads 150 in order to optimally match the workloads 150 to theprocessor cores 130 thereby accounting both for the contemporaneousstatus 120 of the processor cores 130 and also the contemporaneousoperational characteristics 110 recorded for the workloads 150.

The process shown in FIG. 1 can be implemented within a parallelcomputing data processing system. In yet further illustration, FIG. 2schematically shows a parallel computing data processing systemconfigured for dynamic optimization of thread assignments forapplication workloads in an SMT computing environment. The system caninclude a host server 210 comprising at least one processor and memory.The host server 210 can support the execution of an SMT computingenvironment 220 providing access for different threads 260 in a threadpool 230 executing in one or more processor cores to different workloadsof an application. A characterization module 280 can be coupled to theSMT computing environment 220.

The characterization module 280 can include program code that whenexecuted in the memory of the host server 210 can monitor andperiodically record the operational status of the different processorcores hosting different threads 260 in a resource table 270 disposed inan SMT data store 240. In this regard, the operational status of eachprocessor core can include number of SMT (processing) threads hosted onthe core, an identification of each processing thread 260 hosted on it,and one or more measured coefficients of the operational characteristicsof the underlying processor core. The program code of thecharacterization module 280 during execution in the memory of the hostserver 210 also can monitor and periodically record the operationalcharacteristics of the different workloads in a workload table 250disposed in the SMT data store 240. In this regard, the operationalcharacteristics can include a measure for each workload both of cyclesconsumed per instruction (CPI) and a variation in the CPI for theworkload from measurement to measurement. The operationalcharacteristics for each workload additionally can include a number ofclock ticks consumed for the workload and a frequency of consumption ofclock ticks for the workload. Finally, the operational characteristicsfor each workload can include one or more of the measured coefficientsresulting from the operation of the workload.

Of note, an optimization module 290 also can be coupled to the SMTcomputing environment 220. The optimization module 290 can includeprogram code enabled upon execution in the memory of the host server 210to review entries in the workload table 250 to identify workloadsdemonstrating stability according to the variance of CPI consumed by theworkloads. Once a workload has been identified as demonstratingoperational stability, the program code of the optimization module 290further can determine the degree of hotness of the workload based uponthe number of clock ticks consumed by the workload.

If the workload is considered to be operating at or above a thresholdlevel of activity, the program code of the optimization module 290 canmatch the operational characteristics of the identified workload to theoperational status of the processor cores hosting threads 260 in thethread pool 230 in order to select an available one of the processorcores best able to accommodate the operational characteristics of theidentified workload. Thereafter, the identified workload can be assignedto the matched one of the processor cores. To the extent that no one ofthe processor cores is determined from the resource table 270 to beavailable for allocation to the identified one of the workloads, thematching of the workloads already assigned to corresponding ones of theprocessor cores and/or the number of threads hosted(enabled) on one ormore of the cores can be re-arranged to optimize the assignment ofworkloads to threads 260 in the processor cores.

In even yet further illustration of the operation of the optimizationmodule 290, FIG. 3 is a flow chart illustrating a process for dynamicoptimization of thread assignments for application workloads in an SMTcomputing environment. Beginning in block 310, an entry for a workloadin the workload table can be reviewed. In decision block 320, it can bedetermined if the workload has achieved stability of operation (inreference to a reference to variance in measured CPI for the workload),and also a threshold level of activity (in reference to a number ofclock ticks consumed for the workload). If not, a next entry in theworkload table can be reviewed and the process can repeat. Otherwise,the process can proceed through block 330.

In block 330, the coefficients for the workload can be compared to thecoefficients of each entry of an available processor thread in theresource table. In this regard, the coefficients can includecharacteristics of a workload in such that each characteristic can referto the utilization of some computing resource on the processor. As such,by way of example, a coefficient can refer to Floating Point Unit (FPU)usage, Fixed Point Unit usage, input/output (I/O) bandwidth consumption,cache and memory access details, to name only a few possibilities. Thus,the coefficients are indicative of the extent to which each workloadutilizes or places demands upon the computing resources of a processor.

In decision block 340, it can be determined if any entry in the resourcetable for an available processor core demonstrates a satisfactoryability to host the execution of the workload in one or more threads. Inparticular, the coefficients of the workload can be compared to othercoefficients of other workloads to ensure that no two workloads arescheduled to the same processor core so as to impart the same processingdemands upon the computing resources of the same processor core.Alternatively expressed, workloads are to be scheduled on processorthreads hosted on a processor core such that each workload receivessatisfaction of a corresponding set of resource requirements withoutinterfering with the resource requirements of other workloads on otherthreads as much as possible.

In decision block 340, if it is determined that an entry in the resourcetable indicates an available processor thread able to host the executionof the workload, the workload can be assigned for execution in one ormore threads of the identified processor core. Otherwise, in block 360the existing assignments of different workloads to different processorcores and/or the number of threads hosted(enabled) on one or more of thecores can be re-arranged to account for the contemporaneously measuredstate of the processor cores and the hotness of different workloads.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, radiofrequency, and the like, or anysuitable combination of the foregoing. Computer program code forcarrying out operations for aspects of the present invention may bewritten in any combination of one or more programming languages,including an object oriented programming language and conventionalprocedural programming languages. The program code may execute entirelyon the user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present invention have been described above withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems) and computer program products according toembodiments of the invention. In this regard, the flowchart and blockdiagrams in the Figures illustrate the architecture, functionality, andoperation of possible implementations of systems, methods and computerprogram products according to various embodiments of the presentinvention. For instance, each block in the flowchart or block diagramsmay represent a module, segment, or portion of code, which comprises oneor more executable instructions for implementing the specified logicalfunction(s). It should also be noted that, in some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

It also will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks. The computer program instructions may also beloaded onto a computer, other programmable data processing apparatus, orother devices to cause a series of operational steps to be performed onthe computer, other programmable apparatus or other devices to produce acomputer implemented process such that the instructions which execute onthe computer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

Finally, the terminology used herein is for the purpose of describingparticular embodiments only and is not intended to be limiting of theinvention. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

Having thus described the invention of the present application in detailand by reference to embodiments thereof, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims as follows:

1-5. (canceled)
 6. A parallel computing data processing systemconfigured for dynamic optimization of thread assignments forapplication workloads in a simultaneous multi-threading (SMT) computingenvironment, the system comprising: a host server comprising memory andat least one processor; an SMT computing environment executing in thememory of the host server and supporting execution of differentworkloads in correspondingly different processor cores hosting differentthreads accessible in a thread pool; a characterization modulecomprising program code executing in the memory of the host server, theprogram code of the characterization module monitoring and periodicallyrecording an operational status of the different processor cores andcorresponding threads and also operational characteristics of thedifferent workloads; and, an optimization module comprising program codeexecuting in the memory of the host server, the program code of theoptimization module identifying by way of the recorded operationalcharacteristics of the different workloads a particular one of theworkloads demonstrating a threshold level of activity, matching arecorded operational characteristic of the particular one of theworkloads to a recorded status of a processor core best able amongst thedifferent processor cores to host execution in one or more of thethreads the particular one of the workloads, and directing the matchedprocessor core to host execution of the particular one of the workloads.7. The system of claim 6, wherein the program code of the optimizationmodule responds to a determination that no one of the processor cores isavailable to host the execution of the particular one of the workloadsby re-arranging an existing assignment of ones of the differentworkloads to corresponding ones of the processor cores to optimizematching of the recorded operational characteristics of the ones of thedifferent workloads to the recorded operational status of the processorcores.
 8. The system of claim 6, the program code of the optimizationmodule identifies by way of the recorded operational characteristics ofthe different workloads a particular one of the workloads demonstratingboth operational stability and a threshold level of activity.
 9. Thesystem of claim 6, wherein the operational characteristics comprises anumber of clock ticks consumed by a corresponding one of the workloads,a higher number of clock ticks indicating a higher degree of activity.10. The system of claim 8, wherein the operational characteristicscomprises a measurement of cycles per instruction (CPI) consumed by acorresponding one of the workloads and a variance in measurements of CPIconsumed by the corresponding one of the workloads over time, a lowervariance indicating greater operational stability.
 11. A computerprogram product for dynamic optimization of thread assignments forapplication workloads in a simultaneous multi-threading (SMT) computingenvironment, the computer program product comprising: a computerreadable storage medium having computer readable program code embodiedtherewith, the computer readable program code comprising: computerreadable program code for monitoring and periodically recording anoperational status of different processor cores hosting threadsaccessible in a thread pool of the SMT computing environment and alsooperational characteristics of different workloads of a computingapplication executing in the SMT computing environment; computerreadable program code for identifying by way of the recorded operationalcharacteristics of the different workloads a particular one of theworkloads demonstrating a threshold level of activity; computer readableprogram code for matching a recorded operational characteristic of theparticular one of the workloads to a recorded status of a processor corebest able amongst the different processor cores to host in one or morethreads execution of the particular one of the workloads; and, computerreadable program code for directing the matched processor core to hostexecution of the particular one of the workloads.
 12. The computerprogram product of claim 11, further comprising: computer readableprogram code for determining that no one of the processor cores isavailable to host the execution of the particular one of the workloads;and, computer readable program code for re-arranging an existingassignment of ones of the different workloads to corresponding ones ofthe processor cores to optimize matching of the recorded operationalcharacteristics of the ones of the different workloads to the recordedoperational status of the processor cores.
 13. The computer programproduct of claim 11, wherein the computer readable program code foridentifying by way of the recorded operational characteristics of thedifferent workloads a particular one of the workloads demonstrating athreshold level of activity, comprises computer readable program codefor identifying by way of the recorded operational characteristics ofthe different workloads a particular one of the workloads demonstratingboth operational stability and a threshold level of activity.
 14. Thecomputer program product of claim 11, wherein the operationalcharacteristics comprises a number of clock ticks consumed by acorresponding one of the workloads, a higher number of clock ticksindicating a higher degree of activity.
 15. The computer program productof claim 13, wherein the operational characteristics comprises ameasurement of cycles per instruction (CPI) consumed by a correspondingone of the workloads and a variance in measurements of CPI consumed bythe corresponding one of the workloads over time, a lower varianceindicating greater operational stability.